Tamerlan Tsarnaev is the alleged mastermind behind the Boston marathon bombings. But in the wake of last week’s attacks, Team 5 Investigates has learned Middlesex County investigators are checking leads to see if the 26 year old who was killed in a shootout with police last Friday had anything to do with a gruesome murder in Waltham on the 10th anniversary of the 9-11 attacks.

Three young men had their throats slashed and marijuana was thrown on their bodies in an apartment on Harding Ave. in Waltham, Mass.. At the time Middlesex District Attorney Gerry Leone described the horrible crime scene, "It was graphic, all there men were killed by sharp wounds to their neck area,” Leone said.

One of the victims, 25 year old Brendan Mess, was a mixed martial arts fighter who used to spar with Tsarnaev in an Allston gym.

Thirty-one year old Erik Weissman was a Cambridge Rindge and Latin grad and body builder.

Team 5 Investigates has also learned the brothers had multiple run-ins with law enforcement. In 2009, Tamerlan Tsarnaev was arrested by Cambridge Police on assault and battery charges for allegedly beating his girlfriend at the time. The charges were later dismissed in court. In 2012 Arlington Police ran a warrant check on Dzhokhar Tsarnaev and checked his green Honda when they were called to a report of an underage drinking party in Arlington Heights.

According to driving records obtained by Team 5 Investigates, his older brother Tamerlan was pulled over by police in Boston, Brookline and Cambridge at least nine times in 4 years.

Russian authorities warned the FBI that Tamerlan Tsarnaev may have been involved in suspicious, radical activities in 2011 but it appears everything came up clean during these run-ins with local law enforcement. As far as the Waltham murder goes, sources tell Team 5 Investigates the older brother was never a suspect but they’re checking out all leads in the wake of the bombings.

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